From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1FzPYw-0001Nd-FR for qemu-devel@nongnu.org; Sat, 08 Jul 2006 23:02:26 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1FzPYu-0001NR-A1 for qemu-devel@nongnu.org; Sat, 08 Jul 2006 23:02:25 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1FzPYu-0001NO-56 for qemu-devel@nongnu.org; Sat, 08 Jul 2006 23:02:24 -0400 Received: from [81.29.64.88] (helo=mail.shareable.org) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA:32) (Exim 4.52) id 1FzPZf-0002Kr-Pm for qemu-devel@nongnu.org; Sat, 08 Jul 2006 23:03:12 -0400 Received: from mail.shareable.org (localhost [127.0.0.1]) by mail.shareable.org (8.12.11.20060308/8.12.8) with ESMTP id k6932KWa010568 for ; Sun, 9 Jul 2006 04:02:20 +0100 Received: (from jamie@localhost) by mail.shareable.org (8.12.11.20060308/8.12.8/Submit) id k6932J9m010565 for qemu-devel@nongnu.org; Sun, 9 Jul 2006 04:02:19 +0100 Date: Sun, 9 Jul 2006 04:02:17 +0100 From: Jamie Lokier Subject: Re: [Qemu-devel] balloon driver Message-ID: <20060709030215.GA10402@mail.shareable.org> References: <946a3fda0607041958p2e5daab3o2c6d3f633aafc089@mail.gmail.com> <200607051552.12914.paul@codesourcery.com> <946a3fda0607081806r56d18980vd00f570de44a1466@mail.gmail.com> <200607090232.55272.mark.williamson@cl.cam.ac.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200607090232.55272.mark.williamson@cl.cam.ac.uk> Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Mark Williamson wrote: > > Even if the guest has to swap, the reasoning is that the guest is in a > > much better position to figure out what to swap than if the host were > > forced to. > > Worse, the guest might decide to swap out a page that's already > swapped in by the host, forcing it to be read in again only to be > immediately written out to disk by the guest :-( ...unless the guest's disk I/O is with simulated DMA or recognisable block-copy instruction sequences, and doesn't look at the data. In that case the emulator can, in principle, keep track of where pages are copied around without being examined, and avoid actually swapping them in. Probably not worth the complexity. -- Jamie